MICROWAVE OVEN WITH ROTARY ANTENNA

摘要

A microwave oven with a rotary antenna for feeding electromagnetic waves to a heating chamber. The antenna has a first antenna portion and a second antenna portion which extend in mutually opposite directions and substantially at right angles to a rotary shaft portion, the length of the first antenna portion being greater than that of the second antenna by approximately one quarter of the wavelength of the electromagnetic waves used and the free end of the first antenna portion being bent substantially at right angles thereto for a length not exceeding one quarter of the wavelength to thereby ensure a uniform electric field distribution within the heating chamber. A dielectric seal plate supporting the rotating shaft of the rotary antenna has a tapered cross-sectional configuration projecting into a waveguide to prevent a sharp change of impedance in the waveguide, whereby spark discharge due to a high frequency electric field is effectively prevented even in the absence of a heating load in the heating chamber.